1. Field of the Invention
The invention relates to a safety shield for flanged pipe couplings. In particular, the safety shield of the invention is constructed so as to be resistant to corrosive chemicals.
2. Prior Art
Flange shields are commonly used for interrupting leakage from pipe joints. They are especially useful if the piped fluid is under pressure and the seal in a flanged coupling ruptures. In such event, the safety shield on the flange prevents spraying or splashing of the piped liquid in the vicinity of the pipe coupling. This is particularly important if the liquid is corrosive or otherwise dangerous on contact to workmen in the vicinity.
Others have made developments in this field. However, to date, these developments have utilized glass cloth, aluminized asbestos and other cloth-like materials to construct the shields, the shields utilizing these materials have been stitched, bonded or sewn together. In practice these materials tend to trap the harmful liquids within the folds and creases of the material. If the material is absorbent, the liquid is absorbed by the material. In either event, workmen replacing the shield become exposed unnecessarily to these dangerous liquids. In fact, these shields are considered to be sacrificial. That is, they are expected to remain unitary just long enough to prevent accidental splashing of nearby workers.
Workers must then carefully remove the contaminated remains without exposing themselves to the hazardous chemical which attacked the shield. If the leak is stopped before the shield is destroyed, the leaking chemical becomes trapped in the folds and layers of the material creating a potential hazard to workers removing same.
These materials deteriorate when exposed to ultraviolet light, resulting in embrittlement and cracking.
Typical of patents in this field is U.S. Pat. No. 3,850,451 to Roy Matthiessen, which claims a safety shield, for flanged pipe couplings, having a strip of aluminized or glass fiber cloth, with one or more liner strips secured within the shield strip. The shield is secured to the flange with a metal wire whose ends are twisted together.
Another Mattiessen patent in this field is U.S. Pat. No. 3,113,790, which utilizes a sheet of metal, spacing rods, and a plurality of flange sections cut into the longitudinal edge of the shield. While in the specification the patentee states that a suitable synthetic resinous composition could be used, the entire specification's teaching is directed to the use of metal in constructing the shield (see FIGS. 1-6).
Neither device provides adequate protection to workers exposed to corrosive liquids, which would fend to destroy the materials used in these two, cited patents. If not destroyed, the glass fibers tend to trap the liquid within its particular construction, usually corroding the wires securing it to the flange.